In a wireless communication system, there is an OFDMA (Orthogonal Frequency Division Multiple Access) system or OFDM (Orthogonal Frequency Division Multiplexing) system, in which data is mapped to subcarrier signal (carrier wave) which is mutually orthogonal on the frequency axis, and these signals are multiplexed and transmitted in order to improve throughput.
On the other hand, burst error, in which there is a continuous series of error bit in transmitted data, is one major cause of throughput degradation in the wireless communication system. A major cause of the burst error is local declines in amplitude (declines in power) on the transmission path. In particular, when a change in the transmission path is slow, the decline in amplitude in the transmission path continues for long duration in the time direction, and a probability of occurrence of the burst error rises.
In the prior art, packet communication devices is disclosed in which, when reallocating a plurality of channels to a plurality of terminals in response to the burst error, the number of channels which can be transmitted to each terminal and the number of terminals to which each channel can be allocated are combined, so as to allocate the optimal frequency to each terminal (see for example Patent Document 1 (Japanese Laid-open Patent Publication No. 2002-252619)).
Moreover, a transmission and reception device and transmission and reception method are disclosed in which the propagation path state is judged over the entire range of frequencies used by received multicarrier signal, a subband (frequency band) with satisfactory propagation path state is selected by a propagation path judgment unit, an optimal frequency region is identified, and system throughput is improved (see for example Patent Document 2 (Japanese Laid-open Patent Publication No. 2005-244958)).
In addition, there is an adaptive modulation and coding (AMC) in which an encoding and modulation method are changed adaptively on the basis of propagation path state.
However, in Patent Document 1 and Patent Document 2, the burst is not allocated to the frequency band for which the propagation path state is not good, so that the frequency band is not used, and as a result the throughput declines.
Also, in adaptive modulation encoding, the throughput of the communication system declines if a low coding rate and modulation method are selected, whereas a high SNR is preferably to transmit data if a high coding rate and modulation method are selected.